docs: def normalize_lons(l1, l2):
      """
      An international date line safe way of returning a range of longitudes.
  
      >>> normalize_lons(20, 30)  # no IDL within the range
      [(20, 30)]
      >>> normalize_lons(-17, +17)  # no IDL within the range
      [(-17, 17)]
      >>> normalize_lons(-178, +179)
      [(-180, -178), (179, 180)]
      >>> normalize_lons(178, -179)
      [(-180, -179), (178, 180)]
      >>> normalize_lons(179, -179)
      [(-180, -179), (179, 180)]
      >>> normalize_lons(177, -176)
      [(-180, -176), (177, 180)]
      """
      if l1 > l2:  # exchange lons
          l1, l2 = l2, l1
      delta = l2 - l1
      if l1 < 0 and l2 > 0 and delta > 180:
          return [(-180, l1), (l2, 180)]
      elif l1 > 0 and l2 > 180 and delta < 180:
          return [(l1, 180), (-180, l2 - 360)]
      elif l1 < -180 and l2 < 0 and delta < 180:
          return [(l1 + 360, 180), (l2, -180)]
      return [(l1, l2)]